How it works
Oxid Block has two parts. Its ad and tracker blockers give Safari a list of addresses to hide, and Safari does the blocking on your device. Its dark mode extension, when you allow it, restyles the pages you open so they appear dark; that work also happens on your device. The app has no account and no server, and contains no analytics, no advertising and no tracking.
What leaves your device
Nothing about you. The block lists are built into the app, so there is no list to download and no request that says which pages you visit. When you open the “Test my blocker” page, your browser loads that page like any other website. To darken a page’s own stylesheets and images, the dark mode extension may read them again from the same addresses the page already loads them from, without your cookies. It makes no other requests.
What stays on your device
Your settings, whether each extension is turned on, and the sites you have given their own dark mode settings (shown in the app’s site list). They are kept in Safari’s extension storage and the app’s storage on your device, and are never uploaded. The ad and tracker blockers never see the pages you open or the addresses Safari blocks.
Purchases
Oxid Block Pro is bought through the App Store. Apple handles payment; the app only checks, on your device, whether Pro is unlocked.